Uh...the fact that past about level 5 AC no longer matters? I'd rather have a character who just doesn't care about dying than one who gets creamed because someone ignored that AC altogether and made you go splat because he has three or four dozen other ways to kill you?
Past level 5 AC no longer matters? Hmm. What about full attacking dragons? Pouncing chargers?
I wonder what you could mean. Even Solo suggested blink, so that's your miss chance (apart from the monk's quite good stealth skills that add concealment to the lot).
Then touch AC is also less of an issue with such a build.
Saves vs spell attacks maybe? Probably not with a monk.
No-spell-no-SR spell attacks maybe? Can all be countered/handled with the right equipment.
Hmmm.
What could it be from level 5 that makes AC redundant in core?
- Giacomo
PS: Note that while Solo made a laugh out of AC optimisation, even the build he outlined was able to do much, much more than just that.